private static final String DATABASE_NAME = "test.db";
private static final int DATABASE_VERSION = 1;
private final Context context;
SQLiteDatabase db;

private static final String DATABASE_PATH = "/data/data/com.app.army.tab/databases/";
private final String USER_TABLE = "user";


public DatabaseHelperTwinIGE(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    this.context = context;
    createDb();
}

@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {

}

@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}

public void createDb() {
    boolean dbExist = checkDbExist();

    if (!dbExist) {
        this.getReadableDatabase();
        copyDatabase();
    }
}

private boolean checkDbExist() {
    SQLiteDatabase sqLiteDatabase = null;

    try {
        String path = DATABASE_PATH + DATABASE_NAME;
        sqLiteDatabase = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READONLY);
    } catch (Exception ex) {
    }


    if (sqLiteDatabase != null) {
        sqLiteDatabase.close();
        return true;
    }
    return false;

}

private void copyDatabase() {
    try {
        InputStream inputStream = context.getAssets().open(DATABASE_NAME);

        String ourFileName = DATABASE_PATH + DATABASE_NAME;

        OutputStream outputStream = new FileOutputStream(ourFileName);

        byte[] b = new byte[1024];
        int length;


        while ((length = inputStream.read(b)) > 0) {
            outputStream.write(b, 0, length);
        }

        outputStream.flush();
        outputStream.close();
        inputStream.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private SQLiteDatabase openDatabase() {
    String path = DATABASE_PATH + DATABASE_NAME;
    db = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READWRITE);
    return db;
}

public void close() {
    if (db != null) {
        db.close();
    }

}


public String getUserWeigth(String username, String password) {
    String[] column = {"weight"};
    db = openDatabase();

    String selection = "username=? and password = ?";
    String[] selectionArgs = {username, password};

    String weight = null;

    Cursor cursor = db.query(USER_TABLE, null , selection, selectionArgs, null, null, null);
    if (cursor.moveToFirst()) {
        weight = cursor.getString(2);
    }
    cursor.close();
    close();


    return weight;
}

Button btnLogin;
EditText editUsername;
EditText editPassword;
TextView result;
DatabaseHelperTwinIGE databaseHelperTwinIGE;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.tab5twinoge, container, false);


    btnLogin = (Button)view.findViewById(R.id.btnAdd);
    editUsername = (EditText)view.findViewById(R.id.txtNumber1);
    editPassword = (EditText)view.findViewById(R.id.txtNumber2);
    result = (TextView)view .findViewById(R.id.txtResult);

    databaseHelperTwinIGE = new DatabaseHelperTwinIGE(getActivity());

    btnLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String weight = databaseHelperTwinIGE.getUserWeigth(editUsername.getText().toString(), editPassword.getText().toString());

            if (weight != null){
                Toast.makeText(getActivity()," weight = " + weight,Toast.LENGTH_SHORT).show();
                result.setText(weight);
            } else {
                editPassword.setText(null);
                Toast.makeText(getActivity(),"Login failed. Invalid username or password.",Toast.LENGTH_SHORT).show();
            }


        }
    });


    return view;

}